The invention relates to underground geophysical/hydrogeologic measurements, and more particularly to direct measurement of unsaturated water flow in the soils of the vadose zone.
The vadose zone is the zone between the soil surface and the first regional water table. The water flow in the vadose zone is unsaturated.
For a variety of applications, including soil physics, soil chemistry, agriculture, remediation, hydrogeology, and hydrology, it is desirable to measure unsaturated water flow in comprising unconsolidated soils and sediments of the vadose zone. Current systems rely on derived calculations performed using thermal properties, hydraulic conductivity, or vertical moisture content profiles. Other direct systems require trenches, large lysimeters, or large boreholes, which disturb the soil and alter its properties.
It is further desirable to provide direct field measurement of water velocity and chemical fluxes at different depths in the vadose zone. These measurements yield in situ information on water flux and chemical transport through the vadose zone into the groundwater, can be used to calibrate mathematical models and numerical codes, and can also be used to monitor and control the effectiveness of remediation or agricultural procedures.
Accordingly, it is desirable to provide an improved direct measurement of unsaturated water flow in the vadose zone. It is also useful in some cases to determine other hydraulic soil parameters such as unsaturated hydraulic conductivity.